Testing means for fire protection systems



Oct. 11, 1938. s. E. ALLEN TESTING MEANS FOR FIRE PROTECTION SYSTEMS Filed Dec. 22, 1934 M 1.. Rm Y y m i m m E w w a Z, m v r O 2 m 4 W. 6 B 6 -T. Mm m M E n Patented a. 11, 1936 UNITED STATES PATENT OFFICE TESTING MEANS FOR FIRE PBOTBCI'ION SYSTEMS ScottE.Allen,Glcnliidge,N.J.,aflgnoi-to C-O-Two Fire Equipment Company, Newark, N. 1., a corporation of Delaware Application December zz, 1934, Serial do. 75am ing such test. The present invention is more particularly adapted to the alarm systems for protecting a plurality otchambers in each of which a thermostatic switch is provided, the switches individually controlling a common electric signal, such as an alarm bell, or, warning light, or, both.

In general there are two systems now in common use known respectively as the "closed" and the "open" systems. In the closed" 'system, the thermostatic switches are connected in series in a control circuit and are normally closed, but an abnormal rise 0! temperature in any chamber will open the switch in said chamber and this will cause the signal to be electrically operated. In the open system, the thermostatic switches are arranged in parallel across the control system and each is normally open but is adapted to be closed by an abnormal rise 01 temperature in its immediate vicinity.

The present invention is applicable to either the opel'f' or the "closed" system. An object oi! the invention is to provide means for, in eiiect,

cutting out any control unit without disturbing the control circuit to which it is connected, so that such unit maybe tested, as by application '01 heat thereto, or in any other suitable way, to de- 'termine whether it is in proper working condi-' tion. By" this arrangement a test may be conducted without operating the signal and giving a false alarm, and. at the same time, while any unit -is being tested the rest of the units will be free to operate and give the alarm in case of a fire in their immediate vicinity.

With the above-named objects in view and otherswhich will appear hereinafter I shallnow describe a preferred embodiment of my invention and a modification thereof and thereafter shall point out the novelty and scope of the invention in the claims. a

In the accompanying rawing:

Figure l is an electrical diagram of a closed electric alarm system embodying my invention;

Fig. 2 is a viewin vertical section showing one of the thermal control units installed in said system;

Fig. 3 is a view in section taken substantially on the line 3-3 01- Fig. 2, but showing the thermal unit in full; and Y Fig.4isanelectrlcaldiagramoianopenelectric alarm system embodying my invention.

In Figure 1 a set 01 four chambers II, II, I! and I3 is indicated, each chamber having a thermo-sensitive switch I at the ceiling of the chamber. Each switch unit comprises a pair of electric conducting members II and It respectively which have contact points normally each other. The member I! is a bi-metallic strip which is arranged to flex away from themember I! when heated above a predetermined temperature so' as to open the switch.

The thermalswitches ll areconnectedinseries in a'circuit II, II which is supplied with electric current from a suitable source, not shown. Also included in series with the switches is a heating coil 2|. A bell 2i and lamp flare connected in parallel acrosslines II and libyaoonductor 24 leadingtothe line II and aconductor "leading to one pole 26 of a thermostatic switch 21, the other pole 2| 0! which is electrically connected to the line I.

\ sofanlhavedescribedapparatmwhichis wellknownintheartandtowhichperselmake no claim. Itwillbeobviousthatwiththeapparatusassoiar described,anyone oitheswitches ll maybetestedtoseewhethertheswitchwill open when subjected to heat, but'when such a testismadethealarmbellflwillbcsounded andthelamp22willbellghted.' Thiswillgive afalsealarmunlesstheflsnalelementsaredisconnectedfrom the circuit and in such case it maybediillculttodeterminewhethertheswltch hasactuallyopenedbecausetheclmtsliand lcbem mmmabumwmcnmmaw connected to the testing instrument.

enclosed in a cage, cannot very readily be seen. Also during such testing period, if there should be a fire in one of the compartments, there would be no way of distinguishing between a real fire alarm and a false alarm.

To overcome these drawbacks, my invention provides each thermostatic switch M with means for connecting a testing instrument in shunt across the terminals of the switch. The testing instrument is of such low resistance that when the switch is tested and opened by thermal or other means, the circuit I8, I 9 will not be materially affected and consequently the main switch 27 will not be closed. As shown in Figs.

2 and 3 a bracket fill is secured to the inner face of the base plate 3i and carries a pair 'of spring contact plates 4i and 52 which are electrically insulated from the bracket and from each other by means of suitable insulation 63. One of these plates is electrically connected to the binding post 36 and the other to the binding post 3?. These two plates constitute a jack to receive a plug To admit the plug, a grommet 44 of insulating material is inserted through the base plate 3i and is secured in place by means of a nut 45. The plug is of usual construction comprising a tip 46 and abody ,4! electrically insulated from each other and forming terminals of a flexible circuit indicated generally by the reference numeral .43 and extending to an ammeter 50. jThe operation of this device, when a unit is to be tested, is as follows: The plug. 45, 41 is inserted intothe jack thereby connecting the ammeter across the terminals of the members l5 and It. The circuit l8; leis then completed through both the ammeter and the switch l4 under test in parallel. Heat may now be applied to the switch i4 so as to cause the switch to open. When this takes place there will "be no interruption of current passingthrough the heating coil 2i and consequently the main switch 21 will not be closed. The resistance of the ammeter is so low that it will not materially affect the flow of current through the circuit l8, [9, but it is sensitive enough to show anincrease of current flow when the switch l4 opens. In this way, it is possible to cut-out any switch IQ for testing purposes without sounding a false alarm and to determine readily whether the thermo-sensitive switch is in proper operatingcondition, and while such test is taking place the system as a whole will be ready to respond to any abnormal rise of temperature in any of the other chambers; v

The construction shown diagrammatically in Fig. 4 diiiers from that shown in Fig. 1 in the'fact that the thermosensitive switches are adapted for an open systennf As shown in Fig. the main control circuit comprises conductors and 52 which are connected to a suitable source of current' supply not shown. 'I'hermo-sensitive switches 53 are connectedin parallel across the. lines 5| and 52. Switches 53 differ n-bm switches ll in the fact that they are normally open but are adapted to close under the influence of heat. In the line 52 there is a heating unit 54 which is normally deenergized. An alarm bell 55 and a lamp 56 are connected across lines 5| and 52. However, such connection is normally electrically interrupted by a main switch 51 comprising a -pair. of contact members 58 and 55 respective1y.

The member 55 is a bi-metallic thermo-sensitive leaf which lies adjacent the heating unit 54. In

will be heated and, acting on the member 59, will close the switch 51, sounding the alarm 55 and lighting the signal 56. l

The system, as so far described, is well known in the art. My improvements consist in providing a jack in the bridging circuit connecting each switch 53 across lines 5| and 52. This jack comprises a pair of spring contact plates 60 "and 6|, respectively, which are normally in contact, but

' they are adapted to be spread apart by a plug 62 Thus, it is possible to test each of the switches 53 and if when heat is applied to the switch the indicator of the voltmeter shows any voltage this will indicate that the switch has been closed and hence that it is functioning properly.

While I have described two embodiments of my invention, it will be understood that these are to betaken as illustrative and not limitative and that I reserve the right to make various changes in form, construction and arrangement of parts without departing from the spirit and'scope oi my invention as defined in the following claims.

I claim:

1. A. thermostatic control switch for a fire protection circuit, said switch comprising a base plate, a pair of switch elements normally in electrical contact carried by said base plate and projecting from the outer side thereof, one of said elements being adapted to cause a separation' of the elements when subjected to a predetermined temperature, a bracket secured to the base plate at the inner side thereof, a pair of contact members carried by the bracket and insulated from each other and the bracket, and means electrically connecting said elements to said contacting members respectively, said base plate being formed withan aperture alined with said members.

2. A thermostatic control switch for a fire prbtection electric circuit, said switch compris-- 3. A thermostatic control switch for a me protection circuit, said switchcomprising a base "plate adapted to be applied to a recessed support,

" apair of switch elements carried by said plate and operable at a predetermined temperature to open said circuit, a bracket secured to the base plate at the inner side thereof and adapted toproject into said races, 9. pair or normally separated contact members carried by the bracket,

and means connecting said members in parallel with said elements, said base plate being formed with an aperture alined with said members. f 4. A thermostatic control switch for a fire protection circuit, said switch comprising a base plate adapted to be applied to a recessed support, a pair 'of switch elements carried by said plate and operable at a predetermined temperature to close said circuit, a bracket secured to the base plate at the inner side thereof and adapted to project into said recess, a pair of normally contacting members carried by the bracket, and means connecting said members in series with said elements, said base plate being formed with an aperture alined with said members.

5. A thermostatic control switch for a flre protection circuit, said switch comprising a base plate, a pair of switch elements carried by said plate and projecting from the outer sidethereof and operable at a predetermined temperature to close said circuit, a bracket secured to the base plate at the inner side thereof, a pair of bers.

6. A thermostatic control switch for a fire protection electric circuit, said switch comprising a base plate, a pair of switch elements carried by said plate and operable at a predetermined temperature to eiiect an electrical change in said circuit, a bracket secured to the base plate at the inner side thereof, a pair of contact members carried by the bracket, and means connecting said members into said circuit, said base plate being formed with an aperture alined with said members.

SCOTT E. ALLEN. 

